All hearts have been with Boston this past week — and eyes glued to the scene as police closed in on the remaining marathon bomber.

Few moments in history have been as gripping to watch in real time as the lockdown in Boston's suburbs, swat teams splayed on porch roofs, men in camouflage on sidewalks normally used by families in sneakers.

Such horrors seem to be visiting us faster than the nation can prepare for them, or even conceive of them. Who would have imagined a bombing at the Boston Marathon? A massacre at a Connecticut elementary school?

It's deeply saddening to see such violence come to a school and a sporting event. They aren't symbols of America's global influence or federal authority, as were the World Trade Center and the Murrah building in Oklahoma City. They are features of a civil society, places where people put their dreams, happy and hopeful little communities.

Yet there's comfort in knowing that authorities had managed to stave off terrorism strikes for a dozen years until Monday. More than 50 plots have been foiled since 9/11, according to the Heritage Foundation. The nation is prepared.

It's also comforting that when the unthinkable does happens, law enforcement agencies react quickly, bravely and competently. And ordinary people emerge as heroes.

Newtown officers arrived at Sandy Hook Elementary School in less than three minutes — though they couldn't possibly match the speed of bullets that took the lives of 20 children and six women. Staff and students acted with great courage in the massacre.

In Boston, first-responders and spectators saved lives with their fast, brave work. Dozens of people ran toward the blasts, not away from them, to help. A surgeon from Florida, there to watch his daughter run, used his belt as a tourniquet on a man's severed leg. Bystanders like Joe Andruzzi, the ex-lineman for the New England Patriots, carried strangers to safety and staunched their wounds.

Prepared For Disaster

Ironically, the bombings have shown how far this nation has come in protecting itself. Boston may be unique in its preparedness.

First-responders at the marathon had tourniquets and other battlefield dressings on hand. That's unusual for ambulances, but Boston was prepared.

Because the city is considered by the Department of Homeland Security as one of the top 10 targets for terrorism, it's had two citywide disaster simulations in the past two years.

The FBI has taken the lead on the Boston investigation. But agencies at all levels of government can now share information (unlike pre-9/11 days) with the help of "fusion centers," or intelligence-sharing facilities that are funnel points for information. Boston's Regional Intelligence Center taps law-enforcement data — traffic violations, jail records, etc. — and public information like land records.

Facial recognition technology can be used to sift for clues in videos and photos of the bomb site. Fortunately, investigators zeroed in quickly on suspects filmed by a surveillance camera mounted on a department store across the street from the bombing.

And then there are Boston's famed Level 1 trauma centers — hospitals — so close by. They were treating victims within 30 minutes of the blast.

And Grateful For That

No doubt that even more sophisticated security measures will be used from now on at sporting events and schools. The public will be protected from bombs and bullets at places they'd never before thought of as unsafe.

We'll mourn our loss of innocence, the communal sense of security we once took for granted. We'll gripe at the metal detectors and checkpoints that are sure to come.

But we should be grateful that we have been so well-protected till now. And that we have heroes in our midst to help us when the inconceivable does happen.